de Wolff F A, Peters A C, van Kempen G M
Neuropediatrics. 1982 Feb;13(1):10-3. doi: 10.1055/s-2008-1059589.
In a group of 59 epileptic children treated with phenytoin (PHT) and valproate sodium (VPA), either alone or in combination, the following effects were studied: (1) the reciprocal effect on the serum levels of the two drugs, and (2) the enzyme-inducing effects of both drugs. VPA had no effect on PHT levels, but PHT significantly decreased VPA concentrations. PHT enhanced both gamma-glutamyltranspeptidase activity (gamma-GT) and D-glucaric acid excretion (GLA); these effects were potentiated by VPA. VPA alone did not affect gamma-GT, but significantly enhanced GLA.
